Upon patient’s request, several methods can be used to

Upon patient’s request, several methods can be used to remove gingival pigmentation:

Chemical cauterization (21): pigmented tissue can be destroyed by a mixture of
90% phenol and 95% alcohol (12), but the agent is highly damaging to oral tissue
and may have a temporary effect (3), since after a while, melanocytes may start to
migrate from the adjacent free gingiva, resulting in Gingival repigmentation(18,
22, 23).

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Bur abrasion (24-36): surgical bur can used for de-epithelialization. This
technique causes extensive bleeding and post-operative pain, and in fact has
insufficient control over the depth of de-epithelialization (26, 34).

Scalpel surgery (18, 22, 23, 25, 27-30, 33, 35, 37-48): pigmented tissue can be
removed through gingivectomy or removal of attached gingiva via conventional
periodontal surgical procedures. The drawbacks of this approach is include
extensive post-operative pain, prolonged healing, the loss of alveolar bone(49)
(13), as well as the possibility of repigmentation(18, 22).

Cryosurgery (37, 50-60): cryotherapy may be used to remove the pigmented
tissue, but cannot be performed without special instruments and extremely high
technical skills (60-62).

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5. Electro surgery(25, 30, 37, 39, 40, 47, 48, 63),

Gingival grafts(36, 64): pigmentation may be concealed by a gum graft operation,
but it may cause other aesthetic issues such as color mismatch or visible surgery
marks (64).

Laser treatment (31-33, 35, 42, 45, 47, 55, 63): hyperpigmented epithelium may
be removed through a laser ablation operation. In the following, further
information in regard to these techniques is provided. 

Recurrence of pigmentation

The studies with different treatment modalities and follow-up times report different
recurrence rates and intervals (18, 22, 23). 6 studies (out of 16 studies) related to bur
abrasion method report recurrence within 3 to 20 months (25, 26, 33, 36, 50, 65, 66).
Eight studies (out of 23 studies) pertaining to depigmentation by scalpel surgery report
4.25% repigmentation within 4.6 to 90 months after operation (22, 23, 33, 42, 44, 67).
Five studies (out of 12 studies) pertaining to the use of cryosurgery for gingival
depigmentation (50, 52, 55, 58) report recurrence. Only 1 study out of 9 publications
pertaining to electrosurgery show repigmentation within 12 months after surgery(67).
Out of 3 articles on gingival grafts (36, 64, 66), only one does not report repigmentation.
Out of 27 studies in which laser was used for treatment of gingival hyperpigmentation,
repigmentation is reported in three studies with CO2 laser(20, 22, 68) one study with
diode laser (55), two studies with Nd : YAG laser (31, 69), and three studies with
Er:YAG laser (69, 70). In the recent researches, the lowest recurrence rates have been
achieved by cryosurgery, electrosurgery, and laser surgery. Among laser techniques,
operation with diode laser has had the lowest recurrence rate (27).

Laser techniques

Mechanism of laser-tissue interaction

Laser photon energy can be absorbed by chromophores that are of the tissue components.
These elements included melanin, hemoglobin, allied pigmented proteins, hydroxyapatite
and water in oral tissue (71). The chromophores are able to absorb a certain

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electromagnetic spectrum of laser wavelengths (72). The water of the cells after
absorbing the laser photon energy is boiled and thus undergone the micro-explosion,
known as water-induced ablation (73). The chromophores of melanin or hemoglobin also
absorb laser photon energy, resulting in excision and coagulation due to thermal effects
caused by heat accumulation (35).

The gingival depigmentation requires hard and hot lasers, namely high power that has an
output power of >500 mW. The thermal interaction of these lasers is their leading
therapeutic effect, which is occurred because of heat creation and high kinetic energy in
the exposed tissue associated with some consequences in the tissue like coagulation,
vaporization, necrosis, carbonization and denaturation (74).

Laser Device

At present, five types of lasers are available to the aesthetics of dentistry, including argon,
CO2, diode, erbium and pulsed Nd:YAG(75), as described briefly below.

1- Argon lasers: the hemoglobin is capable of absorbing initially the energy emitted from
these wavelengths, resulting in some events in a contact or noncontact mode, such as
precision cutting, vaporizing, hemostasis and coagulation of vascular tissue (76). low
power levels of argon (200–500 mW) are needed to cure composite restorations and
bonding cements, which is found in the range of 514 nm as blue visible light in
electromagnetic spectrum (77, 78). Dental trans-illumination to diagnose dental fractures
and carious lesions also is possible in this wavelength of argon lasers (79).

2- Carbon dioxide lasers: Some of the applications of this kind of laser consist of
vaporizing, cutting and coagulation of soft tissue, as well as gross tissue debulking,
frenectomies, gingivoplasties, gingivectomies and biopsies (80). It is not appropriate
cutting bone and tooth structure by CO2 laser because of its limited power and pulsed
energy.

3- Diode lasers: These kind of surgical laser emit two wavelengths, including about 800-
nm wavelengths produced by aluminum-gallium-arsenide and 980-nm light energy by
indium-gallium-arsenide. These lasers are suitable for rapid cutting, vaporizing and
bacterial removal from tissue adjacent to dental structure in contact mode (81) and for
deeper coagulation in noncontact mode. The effectiveness of 980-nm laser is visible for

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photosclerosis of lesions and little melanin- and hemoglobin-pigmented regions in
removing lesions with the distributions of inhomogeneous melanin (yellow, brown and
black) and oxydeoxyhemoglobin (red, purple, blue) (82). Recently, the novel
SIROLaserBlue, which produce a blue light at 445 nm, has revealed blue laser light in
spectrum of diode wavelength. The hemoglobin and melanin are able to absorb
particularly well this light energy; hence, about 100 times better absorption is seen for the
blue laser beam compared to infrared light. The optical fiber has to be moved several
times slowly over the tissue when using the conventional infrared diode lasers (810, 940
and 970 nm), while very fast, precise, painless cutting can be achieved by the blue laser
beam that enables to couple instantly with the tissue, leading to faster and cleaner cutting
without even touching the tissue. Better absorption attribute makes blue laser light
suitable especially for soft tissue surgery. Traditional indications in germ reduction
(endodontics, periodontics), teeth whitening and the treatment of canker sores and herpes
are might be also achieved by SIROLaser Blue because of its two additional wavelengths,
including the SIROLaser Advance and SIROLaserXtend, that can also be combined with
infrared laser light at 970 nm (83, 84).

4- Erbium family of lasers: Collagen, hydroxyapatite and water components can absorb
the wavelengths of erbium laser, allowing cutting soft tissue, tooth structure and bone.
Two types of erbium lasers are available in dentistry. One of them is yttrium-aluminum-
garnet (Er:YAG) laser to create a wavelength of 2940 nm for cutting teeth easily, quickly,
and precisely(85). The other one is the erbium, chromium: yttrium-scandium-gallium-
garnet laser (Er, Cr:YSGG) with a wavelength of 2790 nm that has surgical properties
identical to the Er: YAG. Concerning the application of theses lasers, the cut is scalpel-
like with very little hemostasis in noncontact mode, and soft tissue sculpting with
adequate hemostasis in the contact mode (86).

Lasers in gingival hyperpigmentation

Successful gingival hyperpigmentation therapy is possible by various dental lasers;
among these, it can be mentioned to heat-producing lasers such as 10,600 nm CO2 laser
(20, 87, 88), 1064 nm Nd:YAG laser (89), 820 nm semiconductor diode laser (24) and
514 nm argon laser (25). Minimal postoperative discomfort and rapid wound healing in
depigmentation procedure have been also observed in non-heat-producing lasers which
are 2940 nm Er:YAG(4, 90) and 2780 nm Er,Cr:YSGG as effective and reliable

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techniques. In the mid-nineties, Er,Cr:YSGG laser was presented and used in 1998
commercially (3).

Many laser systems such as CO2 laser (20), diode laser (91), Nd:YAG laser (89) and
Er:YAG(32) laser have been assessed and evaluated for this purpose. Nevertheless,
limited case reports are found regarding gingival depigmentation with the help of erbium,
chromiumdoped: yttrium, scandium, gallium, and garnet (Er;Cr: YSGG) laser surgery
(92, 93). the U.S. Food and Drug Administration (FDA) confirmed Er; Cr: YSGG laser
and common in dentistry and have used for several soft tissue procedures such as
gingivoplasty, gingivectomy, fibroma removal and granular tissue removal(94); so in this
study, we decided to assess the Er,Cr:YSGG laser application in treating the gingival
hyperpigmentation.

13

LITRATURE
REVIEW

14

The best way to start a research is to search in electronic databases and find related
keywords and terms in other trials. It is considerable that studying of what has been done
in our work field can lead us to minimize biases and errors. In this study we referred to
Google scholar, Pub Med and Cochrane library, which are the most common and famous
databases. Due to updated information, we gathered all the researches until August 30,
2017.

By using the term “Gingival hyperpigmentation” in PubMed, one hundred and eighty
articles were appeared. Most of them were based on the gingival hyperpigmentation,
which have been treated using Laser (4, 20, 31, 32, 35, 42, 45, 47, 55, 63, 67-70, 87-90,
92, 95-99), Scalpel(18, 22, 23, 25, 27, 29, 30, 33, 35, 37-39, 41-43, 45-47, 63, 100, 101),
Bur abrasion(24-27, 30-33, 35, 37, 66, 102-104), Cryosurgery (37, 51-59, 104),
Electrosurgry(25, 27, 30, 37, 39, 47, 63, 101), and Gingival graft (64, 66, 102). Five
studies were found on Er,Cr:YSGG laser therapy in the treatment of gingival
hyperpigmentation, so far (92, 105-108).

Among the main purposes of these investigations is to analyze the outcome of
repigmentation (27). Several researches have reported efforts on secondary outcomes
such as the time of surgery, postoperative pain and complications, but little information is
found about the parameters using a consistent scale. Some of them had duration of
follow-up on pigmentation recurrence around one, three and six months and many of
them followed up less than 1 year (27).

The cryosurgery group with the average follow-up period of 5-60 months was found in 12
studies (37, 51-59, 104), of which five (55, 56, 58, 104) observed recurrent
repigmentation cases. The search showed nine articles (25, 27, 30, 37, 39, 47, 63, 101)
regarding electrosurgery, of which one found repigmentation at 12 months after
surgery(27). Three studies (64, 66, 102) reported depigmentation with gingival grafts,
which one of them stated no repigmentation on the side of the mouth using an acellular
dermal matrix allograft (102); 1.96% recurrent rates were seen. The laser group had 27
publications (4, 20, 31, 32, 35, 42, 45, 47, 55, 63, 67-70, 87-90, 92, 95-99), including
CO2 (20, 42, 87, 88), diode (33, 35, 45, 47, 55, 63, 68, 97-99), neodymium-doped YAG
(Nd:YAG) (31, 69, 89, 96), Er:YAG (4, 32, 42, 69, 70, 90, 95, 98) and Er, chromium :
yttrium, scandium, gallium, garnet (92, 105-108) lasers. All of them revealed the
clinically possible removal of gingival pigmentation. Among these, the gingival

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repigmentation was reported by three studies (20, 68, 92) with CO2 laser, one study (55)
with diode laser, two studies (31, 69) with Nd:YAG laser, and three studies (42, 69, 70)
with Er:YAG laser. Low recurrent rate showed high success rate for the results of
cryosurgery, electrosurgery and laser surgery, 0.32 %, 0.74 %, and 1.16 %, respectively.
The lowest (0.19%) recurrent rate was related to the diode laser compared to other lasers
(27).

When adding laser in search keywords, there were forty two articles, which treated
gingival hyperpigmentation using different kinds of laser (Nd: YAG or Diode or CO2 or
Er:YAG). As mentioned before, in five studies Er,Cr:YSGG laser was employed for
gingival depigmentation (92, 105-108); These studies were conducted in Turkey (92,
108), Islamic Republic of Iran (105), Iraq (106), and Thailand (107). 4 studies were case
reports with one (105, 108) or two (92, 107) and only one study recruited 10 patients and
compare the results of diode and Er,Cr:YSGG lasers for gingival hyperpigmentation in a
split-mouth randomized clinical trial (106).

The studies were experimental and case reports. Some of the experimental studies had
been conducted under controlled conditions (27, 30, 32, 36, 45, 64, 66, 101) or using two
or more methods or two or more different laser types were compared together (25, 27, 29-
33, 35-37, 39, 42, 45-47, 50, 55, 63, 64, 66, 69, 101, 106).

Although most of the reviewed articles reported the case study (27), numerous novel
approaches in medicine were presented. The identification of originality achieve high
sensitivity through case reports and series and consequently are essential for medical
development (103).

Different techniques have been found clinically to fight successfully against the gingival
pigmentation, which all of them reported repigmentation. There are limited comparative
studies on various methods for treating gingival pigmentation (27, 30, 32, 36, 45, 64, 66,
101, 106).

Higher recurrence rates have been reported for bur abrasion and scalpel surgery (8.99%
and 4.25%, respectively) compared to cryosurgery (0.32%), electrosurgery (0.74%) and
lasers (1.16%). Therefore, some evidence suggests that electrosurgery, cryosurgery, and
laser surgery are more reliable to treat gingival melanin pigmentation compared to bur
abrasion or other methods (104, 109). There are some efforts to assess various laser

16

devices as alternative or adjunctive equipment to conventional and mechanical procedures
used to treat periodontal and peri-implant diseases (27). One of the effective, easy to use
and reliable methods in gingival depigmentation is laser ablation. Reportedly on CO2
laser, repigmentation had been stated in 10 of 35 patients at 6 months (42), and 4 of 10
patients (88) and 2 of 10 patients at 24-month follow-up (20). One in 10 patients showed
repigmentation at 18 months followed by diode laser in a study (55). Concerning the
gingival repigmentation within three papers on the Er:YAG laser, eight of 35 patients at
6 months(42), one of five at 3 months(70) and one of three 36 months(69) had this
aesthetic problem. The gingival repigmentation was found in one of three cases at 1
month(31), and in both of two cases at 12 and 24 months (69) using Nd:YAG laser.
Reportedly, the diode laser has had the lowest recurrent rate (0.19%) in the laser group.
The selective photothermolysis is the principle of pigmentation therapy by laser (110).
The laser light has been demonstrated to be at a wavelength specific and well absorbed by
the particular chromophore being treated. The diode laser wavelength is 810 nm, causing
absorption of high-level energy by soft tissues, water, and chromophores, such as melanin
and oxyhemoglobin (111). The absorption spectrum range of melanin is 351–1,064 nm
(112). Among laser systems, the optimal absorption coefficient of water can be seen in
2,940-nm wavelength of Er:YAG laser (111), it does not coincide with the absorption
spectrum of melanin. One of the ideal target chromophore for the diode laser is melanin.
According to the findings, the highest clinical effect of the diode laser is on the melanin
depigmentation (27). There are needs to further clinical evidence due to a lack of data
which may be lead to difficulties in making clinical decision.